The present application claims benefit of Great Britain Application No. 9726621.7 filed Dec. 16, 1997.
The present invention relates generally to telecommunications systems, and more particularly to techniques for handling signaling information in a telecommunications system.
In a typical telecommunications system, a subscriber terminal may be located at a subscriber""s premises for handling calls to and from that subscriber. One or more lines may be provided from the subscriber terminal for supporting one or more items of telecommunications equipment located at the subscriber""s premises. Further, a central terminal may be provided for controlling a number of subscriber terminals, and in particular for managing calls between a subscriber terminal and other components of a telecommunications network.
Typically, for incoming and outgoing calls to and from subscriber terminals, signaling information will be generated to cause the necessary signaling functions to be performed to establish and manage incoming and outgoing calls. This signaling information needs to be correctly managed and routed by the telecommunications system to ensure that the calls are handled correctly.
Nowadays, there is an ever-increasing demand for telecommunications networks to be able to support more users, and this has led to the development of techniques to enable telecommunications systems to support more and more subscriber terminals, and hence more users. This development has also led to an increase in the number of modules, e.g. processing cards, making up the telecommunications system, and an increase in the complexity of the interfaces between these various modules. For example, it may be the case that a plurality of modules all interface directly with a single module (a xe2x80x98many-to-onexe2x80x99 interface).
The above developments have increased the complexity involved in correctly managing and routing the signaling information between these various modules. Hence, it is an object of the present invention to provides an efficient interface mechanism for handling the routing of signaling information between modules of a telecommunications system.
Viewed from a first aspect, the present invention provides a telecommunications system for connecting to a telecommunications network and for routing telecommunications signals between the telecommunications network and a subscriber terminal of the telecommunications system, the telecommunications system comprising an interface mechanism for passing signaling events over a communications link between modules of the telecommunications system separated by the communications link, the interface mechanism comprising: a network-side object on the telecommunications network side of the communications link for receiving a first signaling event from a first module of the telecommunications system and for generating a first signaling message to represent the first signaling event; a user-side object on the subscriber terminal side of the communications link for receiving a second signaling event from a second module of the telecommunications system separated from said first module via the communications link, and for generating a second signaling message to represent the second signaling event; the network-side object being arranged to pass the first signaling message to the user-side object over the communications link for subsequent processing by modules on the subscriber terminal side of the communications link, and the user-side object being arranged to pass the second signaling message to the network-side object over the communications link for subsequent processing by modules on the telecommunications network side of the communications link.
In accordance with the present invention, a flexible interface mechanism is provided for handling signaling information that needs to be routed between modules of the telecommunications system. In addition to traditional one-to-one interfaces between two modules, the mechanism can also efficiently manage one-to-many and many-to-one interfaces, where a single module may need to interface to a plurality of modules at the other end of a communications link.
In preferred embodiments, the first module and network-side object are provided within a concentrator of the telecommunications system, the concentrator being arranged to transmit signals to and receive signals from the telecommunications network in an unconcentrated format, and to transmit signals to and receive signals from a central terminal of the telecommunications network over the communications link in a concentrated format.
This approach enables the telecommunications system to operate in a Demand Assignment mode of operation, where the total number of subscriber terminals provided by the telecommunications system exceeds the number of traffic-bearing channels available for handling calls.
Preferably, the second module and user-side object are provided within a central terminal of the telecommunications system, the central terminal being arranged to communicate with the subscriber terminal. Hence, in preferred embodiments, a central terminal manages communications with the subscriber terminal, and a concentrator is located between the telecommunications network and the central terminal to perform concentration on incoming signals, and to unconcentrate outgoing signals.
In preferred embodiments, the telecommunications system further comprises a call manager, responsive to an indication that a call is being initiated to generate as said first module a call object to handle signaling events associated with that call. Hence, in such embodiments, a separate call object is generated for each call.
For an incoming call, the call object is preferably arranged to receive a setup signaling event, and to cause the network-side object to generate a setup message including as a parameter an identifier of a telecommunications line of the subscriber terminal to which the incoming call is directed, the user-side object being arranged to decode the setup message to determine the setup signaling event, and to transfer the setup signaling event to the second module.
Further, in preferred embodiments, the second module is arranged to cause the second signaling event to be transferred to the subscriber terminal, the subscriber terminal being arranged to process the second signaling event to cause an item of telecommunications equipment connected to the telecommunications line to generate an incoming call indication.
The subscriber terminal may use either wired or wireless communications to communicate with other elements of the telecommunications system. However, in preferred embodiments, the subscriber terminal is arranged to receive and transmit telecommunications signals via a wireless link, and the call object is arranged upon receipt of the setup signaling event to invoke modules of the telecommunications system to allocate a radio slot for establishing the wireless link for the incoming call.
In preferred embodiments, the second module is a signaling port within a central terminal of the telecommunications system, the signaling port being arranged, upon receipt of the first signaling event to cause the first signaling event to be transmitted to the subscriber terminal.
When an incoming call is accepted at the subscriber terminal, then in preferred embodiments an off-hook signaling event indicating that the incoming call is connected is generated to cause an off-hook indication to be transmitted to the second module, the second module being responsive to that off-hook indication to instruct the user-side object to generate a second message identifying that the incoming call is connected.
For an outgoing call from the subscriber terminal, the second module is preferably arranged to receive a setup signaling event and to cause the user-side object to generate a setup message including as a parameter an identifier of a telecommunications line of the subscriber terminal from which the outgoing call is originated, the network-side object being arranged to decode the setup message to determine the setup signaling event, and to transfer the setup signaling event to the first module.
When the outgoing call is accepted by the telecommunications network, then in preferred embodiments a connect signaling event indicating that the outgoing call is connected is received by the first module, and the first module is responsive to said connect signaling event to cause the network-side object to generate a connect message to represent the connect signaling event, the user-side object being arranged to decode the connect message to produce a signaling event for transferring to the subscriber terminal, confirming that the outgoing call is connected.
In embodiments employing a concentrator, the concentrator preferably further comprises an exchange port arranged to transmit signals to and receive signals from the telecommunications network, the exchange port being separated from the first module by a backplane, and a second network-side object and a second user-side object being provided at respective ends of the backplane to handle the communication of signaling events over the backplane.
Viewed from a second aspect, the present invention provides a concentrator for a telecommunications system according to the first aspect of the present invention, the concentrator comprising: a first module; a network-side object providing an interface with a communications link between the concentrator and other elements of the telecommunications network, the network side object being arranged to receive a first signaling event from the first module and to generate a first signaling message to represent the first signaling event for transmission over the communications link; the network-side object further being arranged to receive a second signaling message over the communications link, and to decode that second signaling message for subsequent processing by the concentrator.
Viewed from a third aspect, the present invention provides a central terminal for a telecommunications system according to the first aspect of the present invention, the central terminal comprising: a second module; a user-side object providing an interface with a communications link between the central terminal and other elements of the telecommunications network, the user-side object being arranged to receive a second signaling event from the second module and to generate a second signaling message to represent the second signaling event for transmission over the communications link; the user-side object further being arranged to receive a first signaling message over the communications link, and to decode that first signaling message for subsequent processing by the central terminal.
Viewed from a fourth aspect, the present invention provides a method of handling signaling events in a telecommunications system arranged to be connected to a telecommunications network and to route telecommunications signals between the telecommunications network and a subscriber terminal of the telecommunications system, the method comprising the steps of: providing a communications link between modules of the telecommunications system; arranging a network-side object on the telecommunications network side of the communications link to receive a first signaling event from a first module of the telecommunications system; employing the network-side object to generate a first signaling message to represent the first signaling event; passing the first signaling message over the communications link for subsequent processing by modules on the subscriber terminal side of the communications link; arranging a user-side object on the subscriber terminal side of the communications link to receive a second signaling event from a second module of the telecommunications system separated from said first module via the communications link; employing the user-side object to generate a second signaling message to represent the second signaling event; and passing the second signaling message over the communications link for subsequent processing by modules on the telecommunications network side of the communications link.
By this approach, a flexible interface mechanism is provided for handling signaling information that needs to be routed between modules of the telecommunications system.